Ion thruster with graphite accelerator grid

Abstract

An ion thruster comprises a chamber in which propellant is ionized and an accelerator grid, whereby a flow of ions out of the chamber provides reactive thrust. Charge exchange between neutral atoms of propellant and fast moving ions produces slow ions which impact on the accelerator grid and erode it by sputtering, thus limiting the lifetime of the thruster. The invention includes an accelerator grid comprising a layer which includes graphite providing resistance to erosion and a support layer which overcomes the restrictions on engineering and strength of graphite. The accelerator grid can be constructed by machining a block of graphite 12 to produce an upper surface 13, to which the molybdenum grid 14 can be fixed. The block 12 can then be cut away to permit the graphite to be machined to the same contour as the surface 13. Apertures are drilled through the graphite using the existing apertures of the grid 14 as guides.

Dependencies are inferred from the claim text.